The present invention relates to web roll winding apparatus, particularly apparatus for replacing a finished roll with an empty core in a double-drum web winder, particularly for a web of paper, and to a method of replacing a finished roll by means of such an apparatus.
A drum winder includes a winding station on which a roll is wound with a web, a transfer table across which a push-off device rolls the finished roll from the winding station to an extraction station, and an extraction station including a laterally arranged device for pulling out the winding shaft. Such drum winders are positioned at the place where webs are to be wound, for instance at the end of a paper making machine or following a doubling or lining machine, or the like.
In one known double-drum winder, a winding core is generally covered by a cardboard tube that serves as a support for the wound roll. The core is pressed by hydraulic means along a guide to move against the two parallel drums of the double-drum winder. When a roll has been wound to the desired diameter, the core guide for the core is withdrawn. Then the wound roll is brought to a station for the extraction of the core from the roll, i.e. from the cardboard tube roll support. For this purpose, it is known, for instance, to press the roll off over the front drum and to roll it across a transfer roller table to an extraction station where the core is pulled out by means of an extractor. The roll is then moved away. The core is again provided with a new roll support or cardboard tube and is then moved back over the roller table to the winding station. During this return movement, the core is left to itself over given distances across this roller table. The core is then intercepted again and is repositioned until it finally arrives, as accurately aligned as possible, into the drum bed. However, shortly in front of the drums, the new core must be lowered or raised somewhat in a prism, in order that the finished roll which has just been wound can be rolled over the same roller table to the extraction stations, either above or beneath the empty core. Particularly for webs of large width, the core may be very heavy and may even weigh a ton or more. Upon its return rolling, there is the danger that the core will cant or jam. This can cause damage both to the core itself as well as to the drum. Handling is difficult and complicated and there is also a danger of accidents. The change-over times for substituting new cores are relatively long.
In another known roll winding apparatus, the roll is grasped by one lever of a double-armed lever mounted in a frame and is conveyed in an arc in the direction of travel to a delivery or extraction station. At the same time, a new core is brought to the winding station by the other end of the lever. Although the turnover time is shortened and handling is simplified, the disadvantage of this apparatus, which in itself is very suitable, is that the core must have such flexural strength that it can support a full roll. Thus, the diameter of this core must be of a certain minimum size.
Examples of such double-drum winding apparatus as are described above can be found in U.S. applications Serial Nos. 129,675, filed Mar. 12, 1980, now U.S. Pat. No. 4,304,368 and 165,954, filed July 3, 1980, now U.S. Pat. No. 4,324,369 both by Bernhard Bartmann and both assigned to the assignee hereof.